I went with Raymond Jean Bourque in the poll.
I tossed out Paul Coffey because he was really an average D-man at best. I then tossed out Scott Stevens because while he was a great D-man (his worst +/- season was even in 1985-6), he just couldn't match Lidstrom and Bourque in offense.
The tie-breaker for me was offensive skill. People sometimes forget that Bourque was just below a point-a-game player in his career (0.980 PPG, 1579 -- 410-1169, over 1612 games), and was still a good 2-way defenseman into the twilight of his career. In terms of best D-men ever, I'd probably put Bourque in the top 5 at #3, behind Bobby Orr and Denis Potvin, and just ahead of Larry Robinson).
My final ranking: Bourque, Lidstrom, Stevens, and then Coffey.